Run tests every day at 12:00 AM (#1497)

.github/workflows/pr_tests.yaml

@@ -1,8 +1,10 @@
 name: Run all tests
 
 on:
+  schedule:
+    - cron: "0 0 * * *"
   pull_request:
-    types: 
+    types:
       - opened
       - synchronize
   # https://docs.github.com/en/repositories/configuring-branches-and-merges-in-your-repository/configuring-pull-request-merges/managing-a-merge-queue#triggering-merge-group-checks-with-github-actions